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Car Amplifier Troubleshooting Guide

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by: Seth Wilde

Follow this basic car amplifier troubleshooting guide to help you determine possible problems with your amplifier.  Basic errors are most often the cause of sound system problems.  A majority of these installation errors can be easily fixed by yourself.  If you are experiencing any of the problems listed below, try some of the solutions that we offer.


Amp Will Not Power

  1. Check the remote turn on wire and power wires voltage.
  2. Check continuity on ground wire.
  3. Remote wire needs at least 5 volts to trigger the amp.
  4. Power wire should be at around 12 volts with the car off, 14.4 volts with the car on.
  5. If these are all correct, check the fuses on the amp and the in-line fuse. Check to see if they are blown. You can also check them with a volt meter, each side should read 12 volts.
  6. If all of these have been followed and there is still no power, the amp is defective.

Protect Light Upon Powering On

  1. Follow the steps above regarding a loss of power. If the protection light is on, unplug your speaker wires. If the light turns off, check your speakers and subwoofers for defects. Check to make sure the speakers or subwoofers are not blown, and check to make sure they are not grounding out. Sometimes when mounting a speaker, one of your wires will become loose and may touch metal causing the speaker to short out.
  2. If these have been followed and the light is still on, the problem could be with the RCA cables or source unit. The RCA's are most likely pinched, grounded or burnt.  To trouble shoot your RCA cables grab an extra pair and connect them from your source to the amp. If the light goes away, the problem is with your cables.

Clipping

  1. First, be sure that your amp has enough power to push the woofer. If it is under powering the woofer, it will wear the amp out and cause it to clip (distort). If there is enough power for the woofer, unplug your speaker wires and let it play. Keep your RCA cables, power and ground connected. If the amp is not clipping after unplugging speaker wires, either the speaker wire is burnt or your speakers are shorting out.
  2. Check your speaker/subwoofer to see if they are blown, or grounding out.
  3. If your amp is still clipping after unplugging your speaker wire, check your ground. If could have been knocked loose from going over a speed bump or from your sub woofer rattling it loose. Make sure you check the ground on the amp and grounding source.

No Output

  1. Check to make sure the amp is turning on, if not, then follow 'Amp Will Not Power' steps.
  2. If the amplifier is turned on but still has no output, check your source unit.
  3. To trouble shoot your source, grab an extra pair of RCAs, connect them from your source to the amp.
  4. If your amp has output, you may have a bad RCA or a bad channel on your source. You can also take a 3.5mm cable with RCA ends and plug it into your amp to see if you get output or not.
  5. If you still have no output, try using an external speaker, one that is not installed in your car.
  6. If you have output from the external speaker, then the problem is with your speakers, (see above).
  7. Make sure that the amplifier's setting and crossovers are tuned properly. For example: make sure that the low-pass filter and the subsonic filter do not conflict with each other, otherwise they will cancel out all audio signals coming from the source.
  8. Also as a side note, some amps have a slave and master setting, check to make sure it is on the master setting if not connected to another amp.


Distortion, Background Noise, Crackling, and Hissing in the Speakers

  1. First check to see how your wires are ran. If your RCA cables and speaker wire are ran alongside your power and ground cables they will pick up feedback and distortion.
  2. If this isn’t the case, unplug the speaker wire and see if the noise goes away. There should be absolutely zero noise through your speakers now.
  3. If you are still hearing a noise, check your ground and make sure you have good continuity.
  4. If after following these steps your problem is fixed until you plug everything back in, you’re going to want to check your source. If your source is picking up distortion and sending it to the amp, the amp will make the distortion worse.
  5. If all these have been followed, you may have a bad amp.


Subwoofer, popping, slapping

  1. Make sure the box is the right specs for your woofer.
  2. Check to make sure woofer(s) is wired to the correct impedance. Use the Subwoofer Wiring Diagrams to help with this.
  3. Also be sure that the mount surround is air tight or else air will leak from the box causing a “farting” sound.
  4. Check the power ratings of your amp and sub, if the amp is over powering the woofer you will need to reconfigure your amp, turn your gain down on your head unit and make sure all EQ’s are zeroed. Next, turn down your bass boost and adjust all of your settings accordingly.
  5. If your amp is under powering your woofer and you are getting distortion, you can try using a bigger box or by adding polyfil to help compensate (polyfil will make the subwoofer think the box has more volume by slowing down the movement of air).
  6. You can also compensate under powering your woofer by using a line driver to give your amp more voltage.

Engine Whine

  1. The biggest cause of engine whine through amplified speakers is the ground. Check the ground on your source first, if the source is sending engine whine into your amp, it will be worse through the speakers. Most of the time the source is grounded to the factory ground which is not an acceptable ground for aftermarket units because they are far more sensitive to energy than a stock unit.
  2. Check the ground on the amplifier. The best place to have it grounded is on the negative terminal of your battery, but if your amp is in the trunk and your battery is under the hood that will be too long of a ground cable. The maximum length your ground should be is 3 feet, any longer than that will put the amp at risk for engine noise. If you cant get to the battery with a short enough ground, use a clean chassis ground with no paint on the ground. Keep in mind that just because it is metal does not mean it is a ground.
  3. Check to make sure your RCAs are not run alongside your ground and power wire, this will pick up engine noise.


Overheating Amplifiers

  1. Check your install site. Is your amp in a place where it has good air flow? This is a major cause of overheating.
  2. Check your wiring. Are your speakers or subwoofers wired together at an impedance the amp is stable at? Using the Subwoofer Wiring Diagram can assist with this.
  3. If that is not the cause, then while the system is playing check your voltage at the amplifier. If the voltage is dipping below 12 volts your amplifier is being starved for power causing it to work much harder.
  4. Check your ground with a volt meter. Do you have a clean connection and great contact with the grounding site?
  5. If none of these are the cause, it is likely that your amplifier is defective.


Overheating Car Radio Amplifier

  1. Check the installation. Are wires blocking the fan on your head unit?
  2. Check your wiring. Are any wires shorting out on a ground? Or maybe two wires making contact with each other?
  3. Make sure your speakers are not an impedance that the head unit is not stable at.
  4. Check your ground with a volt meter. Do you have a clean connection and making good contact with the ground?
  5. If none of these are the cause, it is likely your head unit is defective.


Please keep in mind that this is a basic trouble shooting guid and the first things you want to check for when testing for a defect. Hundreds of tiny things can cause major problems for a car audio system. Remember to always read the manual! This can save you embarrassing mistakes; like not pushing the power button on your head unit when you first install it. Your manual will help you out a lot. Always double check your install, then check it again. Taking a little time to troubleshoot can save you days or even weeks of time instead of waiting for an exchange or repair, only to have the item installed again and experience the same “defect”. Just take the time to read this guide before returning an item for warranty purposes. It could save you time so you can enjoy your system sooner and it can save you money not having to pay for shipping, un-installation or reinstallation.

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